Is it possible to do a sparse checkout without checking out the whole repository first?

Question

I\'m working with a repository with a very large number of files that takes hours to checkout. I\'m looking into the possibility of whether Git would work well with this kin

Answer 1

Based on this answer by apenwarr and this comment by Miral I came up with the following solution which saved me nearly 94% of disk space when cloning the linux git repository locally while only wanting one Documentation subdirectory:

$ cd linux
$ du -sh .git .
2.1G    .git
894M    .
$ du -sh 
2.9G    .
$ mkdir ../linux-sparse-test
$ cd ../linux-sparse-test
$ git init
Initialized empty Git repository in /…/linux-sparse-test/.git/
$ git config core.sparseCheckout true
$ git remote add origin ../linux
# Parameter "origin master" saves a tiny bit if there are other branches
$ git fetch --depth=1 origin master
remote: Enumerating objects: 65839, done.
remote: Counting objects: 100% (65839/65839), done.
remote: Compressing objects: 100% (61140/61140), done.
remote: Total 65839 (delta 6202), reused 22590 (delta 3703)
Receiving objects: 100% (65839/65839), 173.09 MiB | 10.05 MiB/s, done.
Resolving deltas: 100% (6202/6202), done.
From ../linux
 * branch              master     -> FETCH_HEAD
 * [new branch]        master     -> origin/master
$ echo "Documentation/hid/*" > .git/info/sparse-checkout
$ git checkout master
Branch 'master' set up to track remote branch 'master' from 'origin'.
Already on 'master'
$ ls -l
total 4
drwxr-xr-x 3 abe abe 4096 May  3 14:12 Documentation/
$  du -sh .git .
181M    .git
100K    .
$  du -sh
182M    .

So I got down from 2.9GB to 182MB which is already quiet nice.

I though didn't get this to work with git clone --depth 1 --no-checkout --filter=blob:none file:///…/linux linux-sparse-test (hinted here) as then the missing files were all added as removed files to the index. So if anyone knows the equivalent of git clone --filter=blob:none for git fetch, we can probably save some more megabytes. (Reading the man page of git-rev-list also hints that there is something like --filter=sparse:path=…, but I didn't get that to work either.

(All tried with git 2.20.1 from Debian Buster.)